6.0L Power Stroke Engine and DrivetrainDiscussion of the 6.0L Power Stroke diesel engine and drivetrain in the 2003-Up Super Duties and Excursions. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 6.0L Power Stroke engine.

The batteries are hooked up in parallel so both provide power to start the engine and run the accessories.
I have used two chargers, one on each battery, without any issues. To avoid conflict between the chargers I disconnect one of the batteries' ground cables but others may say that it is not necessary.

One thing to remember if you are having battery problems get new batteries because weak or bad ones will kill the FICM at a cost of about $1100 from Ford or $300 to have yours repaired should be a min of 850CCA
2 stroker

One thing to remember if you are having battery problems get new batteries because weak or bad ones will kill the FICM at a cost of about $1100 from Ford or $300 to have yours repaired should be a min of 850CCA
2 stroker

Thanks for that info. I have two "newer" 1000 cca batteries installed. About 1 1/2 years old now. Just went and got them checked to make sure and showing good.

I have a Battery Tender Plus hard wired into the passerenger side battery so when it sets for over a week i plug it in because when you start you need 48 volts for the injectors to run and if you are low on volts you will kill the injectors also so batteries need to be at a full charge with the cold weather coming and they like a 5w40 Syn oil.
2 stroker

I have a Battery Tender Plus hard wired into the passerenger side battery so when it sets for over a week i plug it in because when you start you need 48 volts for the injectors to run and if you are low on volts you will kill the injectors also so batteries need to be at a full charge with the cold weather coming and they like a 5w40 Syn oil.
2 stroker

Also great info stroker, from what I had been told in the past I didn't think you needed both batteries...but from what you are saying I want to make sure both batteries are charged instead of just the drivers side battery before starting.

What about jumping off from another vehicle, obviously you have no choice than to use one battery or the other...

Quote:

Originally Posted by Idahoser

if you want to use two chargers, then disconnect one of the batteries' negative cable. You don't want two chargers in the same circuit at the same time.

Jump off just like normal battery, if using a battery charger only one is required and it will feed the other battery, if you use two remove postive cable that is how they are hooked together in parallel , cable runs over top your radiator in a sleeve.

I've had some experience with battery chargers and it's good to have a little bit of background information when using/charging.

Most of today's battery chargers sense the battery's condition and will adjust their output accordingly. Almost all of them are not designed to "see" another source while charging and what will likely happen is you'll end up confusing the sensing circuitry and they'll go into "maintenance mode" rather than a charging mode.

Without boring everyone to death with the details - use a good quality battery charger whether it be for simple trickle charging of fully charged healthy batteries or a larger charge rate/charger for batteries that have been drained and need a good bit of refreshing.

Keep in mind that our lead acid batteries (and all batteries of any existing design with the exception of self limiting designs) experience damage when either discharged too quickly beyond design limitations or are overly discharged at any rate. Our starting system flows a huge amount of current during the starting operation. All of that current flow generates a large amount of heat in the starter and also in the batteries themselves.

As far as batteries go - this should be in another post - having two large capacity lead acid batteries does add some complications. Make absolutely sure your connections are all very clean and all cabling is in near perfect condition. If you have any question as to whether both batteries are healthy take them somewhere to have them load tested.

I make a point to advise people to always replace them as pairs because the weakest battery will always drag down the good one to equalize the system.

If you have any question as to whether both batteries are healthy take them somewhere to have them load tested.

I make a point to advise people to always replace them as pairs because the weakest battery will always drag down the good one to equalize the system.

This brings up another question:

I had them load tested and they check out good, but the person who tests them (two different people at different times) agreed that one starts the engine and the other is for accessories which I am now finding is incorrect.

Even though both checked out good, in order to do a proper load test shouldn't they be checked without being hooked up in parallel together?

If one was bad, could they get a false reading from the other battery being hooked to it?

I had them load tested and they check out good, but the person who tests them (two different people at different times) agreed that one starts the engine and the other is for accessories which I am now finding is incorrect.

Even though both checked out good, in order to do a proper load test shouldn't they be checked without being hooked up in parallel together?

If one was bad, could they get a false reading from the other battery being hooked to it?

I've not verified the statement that they are wired in parallel but I do believe it's the case. I know there are those that frequent this site that do have the schematics to verify.

IMHO anyone telling you that one is used for starting and another for accessories without having at least seen the schematic which enables that behavior is just blowing smoke.

I do know it is not uncommon in the gasoline world to add a second battery that is isolated from starting but I don't believe that's the case for 6.0L owners.

I do know that they MUST be disconnected to do a proper load test using a large carbon pile load tester. In theory you could test both but the tester would have to be huge in order to create a large enough load to make the batteries work hard in parallel.

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